1. Field of the Invention
The present invention relates to a spool-driven film winding system for automatically winding a film loaded in a camera by a spool to which the driving force of a motor as a driving source is conveyed. In particular, the present invention relates to a film winding system having a spool which incorporates a driving mechanism including the motor.
2. Description of the Prior Art
In a spool-driven film winding system, the driving force of a motor as a driving source is conveyed to a spool through an appropriate decelerating mechanism, thereby winding a film loaded in a camera. It is known that this type of film winding system can have a simpler construction than that of a sprocket wheel-driven system in which the driving force of the motor is conveyed to a sprocket wheel.
It is also known that the spool-driven system has a motor in the shaft of the spool to reduce the size of the camera.
For conveying the driving force of the motor, a construction in which the driving force is once conveyed outside the spool and then conveyed back to the spool is generally used.
In such a construction, members for conveying the driving force should be positioned in the camera with high precision. In order to avoid such trouble, a construction has recently been proposed, in which the driving force of the motor is conveyed to the spool without once conveying it outside. In such a construction, all the members are incorporated in the spool.
Japanese Laid-Open Patent Publication No. 2-22635 discloses an example of a film winding system having the above construction. According to this system, one through four epicycle gears are used for a compact decelerating mechanism which is incorporated in a spool with a motor, and an inner gear on an output section of the mechanism is integrated with the spool.
In the above conventional film winding system, the mechanical connection for winding a film between a motor as a driving source and a spool is released only when a film rewinding operation which is considered to be normal in the state of general use is required, for example, when all the frames of a film are wound.
Accordingly, the above conventional film winding system involves the following problems. For example, in the case when only the frames which have already been used are to be removed and the remaining frames are to be kept for future use, usually a rear cover of the camera is opened in a dark room to remove the film from the spool and only the frames which have already been used are cut off. Such an operation, which is effected when one or more frames still remain unexposed, is not considered to be normal. Accordingly, the mechanical connection between the motor and the spool is not released in this case. Instead, gears between a pinion provided on an output shaft of the motor and the inner gear are still in an engaged state.
The film is removed from the spool against the mechanical connection, namely, in the state where the mechanism which acts as a decelerating mechanism for winding the film acts, instead, as an accelerating mechanism. Accordingly, rotation of the spool requires a huge rotating driving force, with the possibility of cutting the film or breaking teeth on the gears of the conveying mechanism.
Such a film removal is also effected for in-house production inspection using a test film. The same accidents may occur.